/*
  将下面异步代码使用 Promise 的方法改进
  尽量用看上去像同步代码的方式
  setTimeout(function () {
    var a = 'hello'
    setTimeout(function () {
      var b = 'lagou'
      setTimeout(function () {
        var c = 'I ♥ U'
        console.log(a + b +c)
      }, 10)
    }, 10)
  }, 10)
*/

function genStr(str){
  return new Promise(resolve => {
    setTimeout(()=>{
      resolve(str)
    },50)
  })
}

async function printStr(){
  console.time('ddd')
  const a = await genStr('hello');
  const b = await genStr('lagou');
  const c = await genStr('I ♥ U');
  console.timeEnd('ddd')
  console.log(a + b +c)
}

printStr().then();
